About Zutra "the Pious" ben Kahana, 25th Exilarch Mar Zutra I

Mar Zutra ben Kahana (Rabina I) was a Talmudist, and rabbi, accounted as an Amora sage of the 5th and 6th generation of the Amora era. He began the process of compiling the Talmud with Rav Ashi. The Talmud was ultimately completed by his nephew Ravina II. http://en.wikipedia.org/wiki/Ravina_I

At an early age Rabina was recognized as a teacher, leaving the academy at Maḥoza while Raba was still living ('Er. 63a; Halevy, "Dorot ha-Rishonim," ii. 543-544). Wherever he lived he was recognized as a teacher and judge, and was called upon to render independent decisions ('Er. 40a; Giṭ. 73a). Rabina was on friendly terms with Naḥman b. Isaac (Giṭ. 32b; Hor. 9a), and was a colleague of R. Aḥa (b. Raba), with whom he had many disputations on legal questions, Rabina being inclined to liberal interpretations while R. Aḥa upheld those more rigorous. Rabina's decisions always prevailed, with the exception of three cases in which, contrary to his custom, he advocated stern measures (Ḥul. 93b).

When R. Ashi became director of the Academy of Sura (or Matah Meḥasya), Rabina became a student there, although he was at least as old as Ashi—perhaps even a few years older; however, he was rather the associate of Ashi ("talmid ḥaber") than his pupil ('Er. 63a). Next to Ashi, Rabina had the greatest share in the redaction of the Talmud undertaken by Ashi and his colleagues.

Rabina died seven years before Ashi.

EXILARCH, in Jewish history, “Chief or Prince of the Captivity.” The Jews of Babylonia, after the fall of the first temple, were termed by Jeremiah and Ezekiel the people of the “Exile.” Hence the head of the Babylonian Jews was the exilarch (in Aramaic Resh Galutha). The office was hereditary and carried with it considerable power. Some traditions regarded the last king of Davidic descent (Jehoiachin) as the first exilarch, and all the later holders of the dignity claimed to be scions of the royal house of Judah. Under the Arsacids and Sassanids the office continued. In the 6th century an attempt was made to secure by force political autonomy for the Jews, but the exilarch who led the movement (Mar Zutra) was executed. For some time thereafter the office was in abeyance, but under Arabic rule there was a considerable revival of its dignity.